CONVERGENCE OF INNER ITERATIONS SCHEME OF THE DISCRETE ORDINATE METHOD IN SPHERICAL GEOMETRY

In transport theory, the convergence of the inner iteration scheme to the spherical neutron transport equation has been an open problem. In this paper, the inner iteration for a positive step function scheme is considered and its convergence in spherical geometry is proved.     

随机游走法在混凝土球形骨料投放中的应用

介绍了利用随机游走法进行球形骨料数值模拟投放的方法,并阐述了球形骨料数值模型的生成、投放、游走及有效性判定的条件.骨料模拟投放的算例表明：基于随机游走的球形骨料投放方法能在较少的计算量下获得较高的骨料填充率,骨料投放结果与实际吻合,适用于各种混凝土细观结构的模拟.     

储氢高压容器钢壁中氢的浓度分布规律研究

储氢高压容器中的氢通过渗透会进入容器钢壁并在钢壁中扩散,最终透过容器外表面进入容器存放环境中.在容器钢壁中的氢会引起材料力学性能变化,从而引起容器承载能力变化.要认识这些变化,首先就要了解氢在钢壁中的渗透、扩散规律和浓度的瞬态分布规律.针对球形高压容器外表面满足一般传质边界条件的情况,建立求解容器壁中氢浓度的解析理论模型,导出了容器壁中瞬态氢浓度和渗透到环境中的氢累积量的理论公式.通过解析计算,给出了器壁中氢浓度和氢在环境中的累积渗透量随时间的变化曲线,分析了相应的变化规律.这些公式和规律性认识为后续的容器壁材料力学性能分析和容器承载能力评估提供了前提.     

球形爆炸容器的内部载荷和响应特性

对球形容器内壁压力、温度和容器外壁应变进行了实验监测,为认识容器内部流场演变和容器响应的全过程提供了较系统的实验数据支持。实验结果及分析显示:容器内部流场在载荷来回反射3次后分布相对均匀;由容器外壁应变波形推测容器内部爆炸产物发生较明显的二次反应;各个应变监测位置均出现了应变增长现象,其中容器入口门正对位置的应变增长现象最严重,应变峰值平均值增大系数达到2.88;容器振动主频率为呼吸振动频率,另一主频率约为呼吸振动频率的1/2;容器外壁最大应变约2.510-3,等效应力峰值比容器材料静态屈服应力大了约80%,容器无明显塑性变形。     

平面波在双孔隙介质中球形夹杂上的散射

基于拓展的Biot孔隙介质弹性理论,将波函数展开法推广应用到求解平面压缩波在双孔隙介质中单球形理想流体夹杂上的散射问题中.在低频条件下,给出了问题解析解的形式,包括位移场和应力场.由进一步的数值计算结果可知:P1波和S波的一阶谐波振幅随着基质孔隙率的增大而减小,P2波的谐波振幅则增大,而P3波的谐波振幅基本不受其影响;随着裂隙孔隙率的增大,P1波的谐波振幅逐渐减小,P3波和S波的谐波振幅增大,而对P2波的谐波振幅的影响甚微;频率越高,双孔隙介质的基质孔隙率及裂隙孔隙率对其谐波振幅的影响越显著.     

流向磁场下球形气泡绕流的线性稳定性分析

电磁冶金中氩气通常作为动力和载体将脱硫剂、脱氧剂吹入到液态金属中,因此存在磁场环境下气泡在液态金属中自由运动的问题,而绕流作为自由运动的特殊形态,是研究自由运动问题的第一步.本文通过有限元方法研究流向磁场作用下球形气泡绕流的全局线性稳定性,讨论基本流对时间-方位角模态小扰动的响应,发现了8个不稳定的驻定模态,并绘制它们在Re-Ha参数平面的中性曲线.结果显示方位角波数m=1的驻定模态首先导致第一次常规分岔,该模态已被广泛证实为轴对称绕流中最不稳定的模态,使轴对称尾迹转变为由一对反向旋转涡组成的单平面对称尾迹.同时第一次分岔的中性曲线展示磁场对球形气泡绕流先失稳后致稳的作用.后续分岔依次由定模态导致.这些分岔为认识磁场环境下气泡绕流的尾迹结构提供重要的参考价值.     

PERMANENCE AND GLOBAL STABILITY TO A NONAUTONOMOUS NONLINEAR DISCRETE SINGLE SPECIES SYSTEM

In this paper,we study some permanence and global stability to a nonau- tonomous nonlinear discrete single species system,and obtain some sufficient condition of global stability to the system.     

GLOBAL WEAK SOLUTIONS OF THE RELATIVISTIC VLASOV-KLEIN-GORDON SYSTEM IN TWO DIMENSIONS

In this paper we consider the system of classical particles coupled with a Klein-Gordon field in two dimensions.We establish a-priori-bounds on the solutions of this system with initial data satisfying a size restriction derived from conservation of energy.This result,together with the smoothing of"velocity averaging",yields the existence of global weak solutions to the corresponding restricted initial value problem.The size restriction is necessary since energy of the system is indefinite.Finally,we show that the weak solutions preserve the total mass.     

球形涂层粒子增强复合材料的有效模量

本文通过四相球模型和复合材料的等效介质理论,研究了球形涂层粒子增强复合材料的有效模量性质,得到了这种增强复合材料的有效体积模量和有效剪切模量的理论预测公式。这些结果在特殊情况下,可退化到三相球模型确定的球形粒子增强复合材料的有效模量公式。     

SURFACE METALLIZATION OF CENOSPHERES AND PRECIPITATORS BY ELECTROLESS PLATING

This paper reports the use of a colloidal Pd^0 catalysis system to metallize the surface of precipitators separated from coal fly-ash, and metals such as Cu, Ni etc. are deposited on the precipitators surface. Alternatively, according to the characteristic surface of cenospheres, an Ag coating catalysis system is adopted to first deposit Ag on the cenospheres surface, followed, if necessary, by the deposition of other metals such as Cu, Ni, etc. on the Ag coating to produce monolayer and multilayer metal-coated cenospheres. The surface characteristics and the morphologies of the metal coatings are examined in detail with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) techniques. It can be shown that the quality of metal coatings derived from the Aa coatina catalysis system, is better than that of the colloidal Pd^0 catalysis system.